(a) Field of the Invention
The present invention relates to a lubricating oil composition for two-cycle engines which excels in both cleanliness and anti-seizure property.
(b) Description of the Related Art
Lubricating system of two-cycle engines can be classified into two types, a mixture method lubrication, by which a mixture of fuel and lubricating oil is fed into engines, and a separate oiling system, by which lubricating oil in a tank separated from fuel tank is fed into engines by means of an oil pump. In either case, lubricating oil is fed into engines and burn after completing lubrication. Lubricating oil for two-cycle engines, therefore, is required to have high anti-seizure property and cleanliness and to burn without generating exhaust smoke.
As lubricating oil compositions for two-cycle engines, there have been known those containing as a main component blends of mineral oil or polybutene with light components, such as kerosene (e.g., Japanese Patent Application Kokoku Koho (Publication) No. 57-34317, Japanese Patent Application Kokai Koho (Laid-open) No. 54-160401). However, there have been problems in that those whose main component is mineral oil are inferior in cleanliness, and that those whose main component is polybutene have poor anti-seizure property. Further, those containing mixtures of mineral oil and polybutene are unsatisfactory in both properties.